5. Eat like a Greek

"We know that omega-3 fatty acids in fish are very important for maintaining heart health," says Keith Black of Cedars-Sinai. "We suspect these fats may be equally important for maintaining a healthy brain."

Data from several large studies suggest that older people who eat the most fruits and vegetables, especially the leafy-green variety, may experience a slower rate of cognitive decline and a lower risk for dementia than meat lovers.

And it may not matter if you get your produce from a bottle instead of a bin. A study from Vanderbilt University found that people who downed three or more servings of fruit or vegetable juice a week had a 76 percent lower risk for developing Alzheimer's disease than those who drank less than a serving weekly.

6. Spice it up

Your brain enjoys spices as much as your taste buds do. Herbs and spices such as black pepper, cinnamon, oregano, basil, parsley, ginger and vanilla are high in antioxidants, which may help build brainpower. Scientists are particularly intrigued by curcumin, the active ingredient in turmeric, common in Indian curries. "Indians have lower incidence of Alzheimer's, and one theory is it's the curcumin," says Black. "It bonds to amyloid plaques that accumulate in the brains of people with the disease." Animal research shows curcumin reduces amyloid plaques and lowers inflammation levels. A study in humans also found those who ate curried foods frequently had higher scores on standard cognition tests.

7. Find your purpose

Discovering your mission in life can help you stay sharp, according to a Rush University Medical Center study of more than 950 older adults. Participants who approached life with clear intentions and goals at the start of the study were less likely to develop Alzheimer's disease over the following seven years, researchers found.